1.
Double-V and double-U butt welds are used for plates of thickness
A
1-5mm
B
5-10mm
C
10-15mm
D
over 15mm
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Double-V and double-U butt welds are used for plates of thickness
1-5mm
5-10mm
10-15mm
over 15mm
Acetylene is a fuel gas for gas cutting & welding composed of
7.7 of carbon & 92.3 % of hydrogen
92.3% carbon & 7.7 % hydrogen
100% carbon
50% carbon & 50% hydrogrn
Which of the gases can be used to form a protective envelope in arc welding?
Oxygen and Carbon dioxide
Hydrogen and Helium
Oxygen and Helium
Helium and Carbon dioxide
The size of the cutting nozzle used in oxy-acetylene cutting process depends mainly on
thickness of metal to be cut
purity of oxygen
duration of cut
type of cutting blowpipe
In gas cutting, if too little cutting oxygen is supplied
the metal will be cooled down
the kerf will be narrow
the kerf will be wide
the metal will fail to cut completely
The function of the central hole in the tip of the cutting blowpipe is
Supply oxygen for preheating
Supply acetylene for preheating
Supply oxygen for cutting
Supply acetylene for cutting
Cast iron contains two elements, which make it difficult to cut it by gas cutting. What are these elements?
Sulphur and phosphorous
Silicon and graphite
Graphite and phosphorous
Silicon and sulphur
Which one of the following is the type of transformer used in arc welding?
Step down
Step up
One-to-one
Capable of increasing supply voltage
The correct colours for oxygen and acetylene hoses are:
Red for oxygen and blue for acetylene
Black for oxygen and red for acetylene
Black for oxygen and maroon for acetylene
Red for oxygen and maroon for acetylene
In DC welding heat distribution is possible between electrode and the base metal due to the change of polarity. The distribution of heat is
Psitive 2/3 and negative 1 /3
Positive 1 /3 and negative 2/3
Positive 3/4 and negative 1/4
Positive 1/4 and negative 3/4
Neutral flame in gas welding contains
oxygen & Actylene in equal proportion
More oxygen than Acetylene
less oxygen than Acetylene
None of the above
The correct flame for preheating before cutting is
oxidizing flame
neutral flame
carburising flame
slightly carburizing flame
The welding machine, which is used to convert AC welding supply to DC welding supply is
Motor generator set
Engine generator set
Rectifier set
Welding transformer
In a gas cut plate, the cut is high quality although there is some surface roughness caused by vertical drag lines. This is due to
less preheating flame
impure cutting oxygen
too slow cutting speed
smaller size cutting nozzle
If L (mm) is the length of the inner cone of the flame, the tip-to-metal distance should be
L mm
L + 2 mm
L + 4 mm
L + 6 mm
The size of a welding machine is determined by
Input amperage
Output amperage
Open circuit voltage
Closed circuit voltage
The arc utilized in electric arc welding is a
High voltage, high current discharge
Low voltage, low current discharge
Low voltage, high current discharge
High voltage, low current discharge
If a worker has suffered from electric shock, he should be
given an alcoholic drink
given a cold drink
made to walk
kept warm and covered
Which type of fire extinguisher is used in a welding shop?
Foam type extinguisher
Dry powder extinguisher
extinguisher
Halon extinguisher
The position in which it is easiest to weld is
Flat
Vertical
Horizontal
Overhead